There are nearly 3 billion fewer wild birds in the skies of North America today than there were in 1970, according to a comprehensive new study.
Researchers from eight different institutions, including the Cornell Lab of Ornithology, nonprofit American Bird Conservancy and Canada’s National Wildlife Research Centre, analyzed population changes across 529 breeding bird species in the United States and Canada.
They discovered a 29% net loss of the North American bird population over the last 48 years ― a decline experts say could have a devastating effect on the continent’s food networks and ecosystems.
“People need to pay attention to the birds around them because they are slowly disappearing,” Kenneth Rosenberg, the study’s lead author and a Cornell University conservation scientist, told The Associated Press. “One of the scary things about the results is that it is happening right under our eyes. We might not even notice it until it’s too late.”
Rosenberg and his colleagues used data from several independent sources, including the North American Breeding Bird Survey and the Audubon Christmas Bird Count, allowing them to factor in bird tallies from thousands of volunteers since 1970.
The researchers also analyzed roughly a decade of data from 143 weather radar stations to estimate changes in migratory bird populations.
The losses affected many of the most common and beloved North American species, including sparrows, warblers, finches and swallows. The populations of both eastern and western meadowlarks have also plummeted, and the numbers of bobwhite quail are down 80%, Rosenberg said.
Some bird populations have avoided decline, though, and others ― including waterfowl like ducks, geese and swans ― have actually grown thanks in part to hunters’ conservation efforts.
The study, published Thursday in the journal Science, didn’t delve into what’s causing the population decline, but experts say habitat loss is likely the top reason, followed by cats and window collisions.
“Every field you lose, you lose the birds from that field,” Rosenberg told the AP. “We know that so many things are killing birds in large numbers, like cats and windows.”
A campaign called #BringBirdsBack, in partnership with the American Bird Conservancy, Audubon, and several other research and conservation organization, suggests seven actions people can take to mitigate bird losses.
Some of the steps include installing screens or reflective material on windows to help reduce bird collisions, keeping cats indoors, adding native plants to yards, and avoiding the use of pesticides around your home and garden.